What does Exodus 8:30 mean?

After another refusal to release Israelite slaves (Exodus 5:1–4), God sends another plague (Exodus 3:19–20). Pharaoh begs Moses to end the catastrophe by appealing to God on his behalf (Exodus 8:28). Moses agrees but warns the Egyptian king not to lie as he did before (Exodus 8:29). Moses fulfills his end of the agreement. He leaves Pharaoh—probably having met in the palace—and speaks to God so the swarms of flies will dissipate.

Of course, God and Moses both know that Pharaoh will not keep his word (Exodus 3:19–20). It will take ten plagues, each more devastating than the last, before he actually allows the people to leave (Exodus 12:30–31, 41). Even then, he will change his mind and pursue Israel (Exodus 14:6–7), resulting in the loss of his army and probably his own life (Exodus 14:26–28).